JAVA 범례 14) 범 형
19656 단어 자바
14.1 범 형 기초
실례 255 범 형 에 대한 간단 한 예
import java.util.Date;
public class MyFirstGeneric<T> {
T t; //t T, ，
MyFirstGeneric(T t) {// T
this.t = t;
}
// T
T getT() {
return t;
}
// T
void printType() {
System.out.println("Type of T is:" + t.getClass().getName());
}
public static void main(String args[]) {
// String Generic
MyFirstGeneric<String> str;
// String Generic
str = new MyFirstGeneric<String>(" ");
//
str.printType();
String string = str.getT();
System.out.println("\tstring=" + string);
// Date Generic
MyFirstGeneric<Date> sobj;
// Date Generic
sobj = new MyFirstGeneric<Date>(new Date());
//
sobj.printType();
String time = sobj.getT().toGMTString();
System.out.println("\ttime=" + time);
}
}
인 스 턴 스 256 두 가지 유형의 매개 변 수 를 가 진 범 형
public class MoreParameters<T, V> {
T t;
V v;
//
MoreParameters(T t1, V v1) {
t = t1;
v = v1;
}
// T V
void printTypes() {
System.out.println(" T ： " + t.getClass().getName());
System.out.println(" V ： " + v.getClass().getName());
}
T getT() {
return t;
}
V getV() {
return v;
}
public static void main(String args[]) {
MoreParameters<Integer, Double> tv; //
// ，
tv = new MoreParameters<Integer, Double>(100, 12.56);
tv.printTypes();
int num = tv.getT();
System.out.println("num : " + num);
double dou = tv.getV();
System.out.println("dou :" + dou);
}
}
인 스 턴 스 257 경계 형식 프로그램 예제
//
public class BoundedType {
public static void main(String args[]) {
System.out.println(" ：");
Integer inums[] = { 1, 2, 3, 4, 5 };// Integer
MyTypes<Integer> iobj = new MyTypes<Integer>(inums);//
System.out.println("\tint ：" + iobj.summation());
Double dnums[] = { 1.1, 2.2, 3.3, 4.4, 5.5 };
MyTypes<Double> dobj = new MyTypes<Double>(dnums);// Double
System.out.println("
\tdouble ：" + dobj.summation());
}
}
class MyTypes<T extends Number> {
T[] nums;// Number
MyTypes(T[] obj) {//
nums = obj;
}
double summation() {//
double sum = 0.0;
for (int i = 0; i < nums.length; ++i)
sum += nums[i].doubleValue(); // Number double
return sum ;
}
}실례 258 어댑터 사용 예시
import java.util.*;
//
public class Wildcard {
public static void main(String args[]) {
Integer Ints[] = { 1, 2, 3, 4, 5 };// Integer
Symbol<Integer> integer = new Symbol<Integer>(Ints);// Integer
Double Dous[] = { 1.1, 2.2, 3.3, 4.4, 5.5 };// Double
Symbol<Double> douObject = new Symbol<Double>(Dous);// Double
douObject.printMessage(integer); // integer douObject
List<String> list1 = new ArrayList<String>();// List ， String
// List
list1.add("String");
list1.add(" ");
list1.add(" ");
List<?> list2 = list1;// List ， list1 list2
System.out.println(" List list2 ：");
for (int i = 0; i < list2.size(); i++) {
System.out.println("\t" + list2.get(i));// list2
}
}
}
class Symbol<T extends Number> {
T[] nums;
Symbol(T[] obj) {
nums = obj;
}
void printMessage(Symbol<?> sb) { //
System.out.println(" sb ：" + sb.getClass().getName());
}
}실례 259 범 형 방법 사용 예시
import java.util.Date;
//
public class GenericMethod {
// ， T
public static <T> void genericMethods(T t, char n) {
T t1 = t; // T
System.out.println("[1] " + n + " ：" + t1.getClass().getName());
}
public static <T> void genericMethods(T t) {
System.out.println("
[2] " + t + " ：" + t.getClass().getName());
}
public static void main(String args[]) {
Date date = new Date();
Character k = new Character('A');
//
GenericMethod.<Character> genericMethods(k, 'B');
genericMethods(date);
}
}
인 스 턴 스 260 팬 인터페이스 예제
//
public class GenericInterface {
public static void main(String args[]) {
Double doubleArrays[] = { 56.5, 58.127, 56.2, 5.569, 825.0, 12.36,
510.89 };// Double
Character charArrays[] = { 'A', 'w', 'z', 'Z', 'b', 'u', 'x' };// Character
ComparableElement<Double> iob = new ComparableElement<Double>(
doubleArrays);// Double
ComparableElement<Character> cob = new ComparableElement<Character>(
charArrays);// Character
// MaxOrMin min() max()
System.out.println(" Integer ， ，max= " + iob.max());
System.out.println(" Integer ， ，min= " + iob.min());
System.out.println(" Character ， ，max= " + cob.max());
System.out.println(" Character ， ，min= " + cob.min());
}
}
interface MaxOrMin<T extends Comparable<T>> {//
// ：min() max()
T min();
T max();
}
// ComparableElement Comparable MaxOrMin
class ComparableElement<T extends Comparable<T>> implements MaxOrMin<T> {
T[] mm;
ComparableElement(T[] ob) {
mm = ob;
}
public T min() {// MaxOrMin min() ，
T t = mm[0];
for (int i = 1; i < mm.length; ++i)
if (mm[i].compareTo(t) < 0)
t = mm[i];
return t;
}
public T max() {// MaxOrMin max() ，
T t = mm[0];
for (int i = 1; i < mm.length; ++i)
if (mm[i].compareTo(t) > 0)
t = mm[i];
return t;
}
}
실례 261 범 형 좌표 인쇄 실현
/**
* Created by IntelliJ IDEA. User: leizhimin Date: 2007-9-18 Time: 16:09:37
* ，
*/
public class CoorGeneric {
static void showXY(GenericCoords<?> c) {// ， C XL XL X Y
System.out.println("X Y :");
for (int i = 0; i < c.gcs.length; i++) {
System.out.println(c.gcs[i].x + " " + c.gcs[i].y);
}
}
static void showXYZ(GenericCoords<? extends XYZ> c) {
System.out.println("X Y Z :");
// ， C XYZ XYZ X、Y Z
for (int i = 0; i < c.gcs.length; i++) {
System.out.println(c.gcs[i].x + " " + c.gcs[i].y + " "
+ c.gcs[i].z);
}
}
static void showAll(GenericCoords<? extends XYZT> c) {
System.out.println("X Y Z T :");
// ， C XYZT XYZT X、Y、Z T
for (int i = 0; i < c.gcs.length; i++) {
System.out.println(c.gcs[i].x + " " + c.gcs[i].y + " "
+ c.gcs[i].z + " " + c.gcs[i].t);
}
}
public static void main(String args[]) {
XY td[] = { new XY(0, 0), new XY(7, 9), new XY(18, 4), new XY(-1, -23) };
GenericCoords<XY> gcd1 = new GenericCoords<XY>(td);
System.out.println("GenericCoords gcd2 ：");
showXY(gcd1);
XYZT fd[] = { new XYZT(1, 2, 3, 4), new XYZT(6, 8, 14, 8),
new XYZT(22, 9, 4, 9), new XYZT(3, -2, -23, 17) };
GenericCoords<XYZT> gcd2 = new GenericCoords<XYZT>(fd);
System.out.println("GenericCoords gcd2 ：");
showXY(gcd2);
showXYZ(gcd2);
showAll(gcd2);
}
}
class XY {// XY
int x, y;
public XY(int x, int y) {// X、Y
this.x = x;
this.y = y;
}
}
class XYZ extends XY {// XYZ
int z;
public XYZ(int x, int y, int z) {
super(x, y);//
this.z = z;
}
}
class XYZT extends XYZ {// XYZT ， X： ，Y： Z： ，T：
int t;
public XYZT(int x, int y, int z, int t) {
super(x, y, z);//
this.t = t;
}
}
/**
* （ ）
*/
class GenericCoords<T extends XY> {// ， XY
T[] gcs;
public GenericCoords(T[] gcs) {
this.gcs = gcs;
}
}
14.2 범 형 류 의 계승
실례 262 계승 범 형 클래스 예시
import java.util.Date;
//
public class GenericClass {
public static void main(String args[]) {
System.out.println(" ：");
// ， ，Date ， String
Child<Date, String> cd = new Child<Date, String>(new Date(),
" : ");
System.out.print("\t" + cd.getDob());
System.out.println(cd.getOb());
}
}
class Child<T, U> extends Father<T> {
U u;
public Child(T t1, U u1) {
super(t1); //
u = u1; //
}
public U getDob() {
return u;
}
}
class Father<T> { //
T t;
public Father(T t) {
this.t = t;
}
public Father() {
t = null;
}
public T getOb() {
return t;
}
}실례 263 비 범 형 클래스 계승 예시
//
public class NonGenericcClass {
public static void main(String args[]) {
System.out.println(" ：");
doNonGeneric<String> oa = new doNonGeneric<String>(
"doNonGeneric : ", 125);
System.out.print("\t" + oa.getOb());
System.out.println(oa.getNum());
}
}
class NonGeneric {// ，
double num;
public NonGeneric(double n) {// num
num = n;
}
public NonGeneric() {// num 0.0
num = 0.0;
}
public double getNum() {// num
return num;
}
}
class doNonGeneric<T> extends NonGeneric {// NonGeneric 。
T ob;
public doNonGeneric(T ob, double n) {
super(n);//
this.ob = ob;//
}
public T getOb() {
return ob;
}
}
실례 264 범 형 류 의 유형 식별 예시
// 1
public class GenericRTTI {
public static void main(String args[]) {
MyFirstGeneric<Double> dou = new MyFirstGeneric<Double>(100.0);
MyFirstGeneric<String> str = new MyFirstGeneric<String>("hellow");
if (dou instanceof MyFirstGeneric)// dou MyFirstGeneric
System.out
.println("MyFirstGeneric<Integer> object is instance of MyFirstGeneric");
if (dou instanceof MyFirstGeneric<?>)// dou MyFirstGeneric<?>
System.out
.println("MyFirstGeneric<Integer> object is instance of MyFirstGeneric<?>");
if (dou.getClass() == str.getClass())//
System.out
.println("MyFirstGeneric<Integer> class equals MyFirstGeneric<String> class");
}
}
인 스 턴 스 265 강제 형식 변환 예제
//
public class CastType {
public static void main(String args[]) {
Father<Double> father = new Father<Double>(1.0);
Child<Double, String> child = new Child<Double, String>(200.0, " ");
// ，
if ((Father<Double>) child instanceof Father)
System.out.println(" .");
// ，
try {
if ((Child<Double, String>) father instanceof Child)
System.out.println(" .");
} catch (Exception e) {
System.out.println(e);
System.out.println(" ： .");
}
}
}닦다
인 스 턴 스 266 무한 계 의 닦 기
import java.util.Date;
//
public class BorderWipe<T extends Date> {
// T String
T date;
BorderWipe(T date) {
this.date = date;
}
T getOb() {
return date;
}
}
실례 267 한계 닦 기
//
public class UnBorderWipe<T> {
// T Object
T ob;
UnBorderWipe(T ob) {
this.ob = ob;
}
T getOb() {
return ob;
}
}
14.4 집합 범 형 류
인 스 턴 스 268 Hashtable 의 일반화
import java.util.Hashtable;
//Hashtable
public class HashtableGeneric<K, V> {
// Hashtable
public Hashtable<K, V> hashTable = new Hashtable<K, V>();
// put key value
public void put(K k, V v) {
hashTable.put(k, v);
}
// get key value
public V get(K k) {
return hashTable.get(k);
}
public static void main(String args[]) {
HashtableGeneric<String, String> t = new HashtableGeneric<String, String>();
t.put("key", "Java ");
String s = t.get("key");
System.out.println(" key value ：
\t" + s);
}
}
인 스 턴 스 269 다기 능 붓
import java.awt.*;
import java.awt.event.*;
import java.util.*;
//
public class Paintbrush extends Frame{
private final static int POINT = 0;
private final static int LINE = 1;
private final static int RECTANGLE = 2;
private final static int OVAL = 3;
private int type; //
Point p1;
Point p2;
ArrayList<Point> points = new ArrayList<Point>();
ArrayList<DrawPoint> area = new ArrayList<DrawPoint>();
public Paintbrush(String s) {
super(s);
}
public void mainFrame() {
MenuBar menuBar = new MenuBar();
Menu menu = new Menu(" ");
MenuItem fmi4 = new MenuItem("Exit");
fmi4.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
});
menu.addSeparator();
menu.add(fmi4);
Menu mtype = new Menu(" ");
MenuItem menuItem = new MenuItem(" ");
menuItem.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
type = Paintbrush.POINT;
}
});
MenuItem menuItem2 = new MenuItem(" ");
menuItem2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
type = Paintbrush.LINE;
}
});
MenuItem dmi3 = new MenuItem(" ");
dmi3.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
type = Paintbrush.RECTANGLE;
}
});
MenuItem dmi4 = new MenuItem(" ");
dmi4.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
type = Paintbrush.OVAL;
}
});
mtype.add(menuItem);
mtype.add(menuItem2);
mtype.add(dmi3);
mtype.add(dmi4);
menuBar.add(menu);
menuBar.add(mtype);
setMenuBar(menuBar);
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
addMouseListener(new MouseAdapter() {
public void mousePressed(MouseEvent e) {
p1 = new Point(e.getX(), e.getY());
if (type == Paintbrush.POINT) {
points.add(p1);
repaint();
}
}
public void mouseReleased(MouseEvent e) {
if (type != Paintbrush.POINT) {
p2 = new Point(e.getX(), e.getY());
area.add(new DrawPoint(p1, p2, type));
repaint();
}
}
});
setBounds(50, 50, 640, 480);
setBackground(Color.WHITE);
setVisible(true);
}
public void paint(Graphics g) {
Iterator<Point> ip = points.iterator(); //
g.setColor(Color.black);
while (ip.hasNext()) {
Point p = ip.next(); //
g.fillOval(p.x, p.y, 10, 10);
}
//
int x1, y1, x2, y2;
for (Iterator<DrawPoint> ipp = area.iterator(); ipp.hasNext();) {
DrawPoint pp = ipp.next();
x1 = (int) pp.startPoint.getX();
y1 = (int) pp.startPoint.getY();
x2 = (int) pp.endPoint.getX();
y2 = (int) pp.endPoint.getY();
switch (pp.type) {
case LINE:
g.setColor(Color.green);
g.drawLine(x1, y1, x2, y2);
break;
case RECTANGLE:
g.setColor(Color.red);
g.drawRect(x1, y1, x2 - x1, y2 - y1);
// ， :
break;
case OVAL:
g.setColor(Color.blue);
g.drawOval(x1, y1, x2 - x1, y2 - y1);
break;
default:
break;
}
}
}
public static void main(String[] args) {
Paintbrush drawApp = new Paintbrush(" ");
drawApp.mainFrame();
}
}
class DrawPoint {
public Point startPoint;
public Point endPoint;
public int type;
public DrawPoint(Point sPoint, Point ePoint, int drawType) {
startPoint = sPoint;
endPoint = ePoint;
type = drawType;
}
}
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